Closing the carbon cycle through rational use of carbon-based fuels

Abstract

In this paper, a brief overview is presented of natural gas as a fuel resource with subsequent carbon capture and re-use as a means to facilitate reduction and eventual elimination of man-made carbon emissions. A particular focus is shale gas and, to a lesser extent, methane hydrates, with the former believed to provide the most reasonable alternative as a transitional fuel toward a low-carbon future. An emphasis is placed on the gradual elimination of fossil resource usage as a fuel over the coming 35 to 85 years and its eventual replacement with renewable resources and nuclear power. Furthermore, it is proposed that synthesis of chemical feedstocks from recycled carbon dioxide and hydrogen-rich materials should be undertaken for specific applications in the transport sector which require access to high energy density fuels. To achieve the latter, carbon dioxide capture is imperative and possible synthetic routes for chemical feedstock production are briefly reviewed.

Keywords: Carbon capture and recycle; Carbon dioxide utilization; Methane hydrates; Natural gas; Shale gas.

Fig. 1

CO₂ emissions per kWh of electrical energy generated from a range of different carbon sources. Note that, employing these fuels for electricity generation, carbon dioxide emissions increase with the reciprocal of the power plant efficiency. For example, if a power station with an efficiency of 34 % burns coal (58 % for gas), it emits 1.0 kg carbon dioxide during the generation of one kWh of electricity. Reproduced with permission, http://www.volker-quaschning.de/datserv/CO2-spez/index_e.php

Fig. 2

Terrestrial organic carbon distribution in gigatons. Land: soil, biota, peat, detritus; Oceans: dissolved organics, biota; Atmosphere: primarily methane; Fossil fuels: recoverable and non-recoverable coal, oil, and natural gas (carbon in rocks and sediments is excluded and 10⁴ Gt methane in hydrates is equivalent to 14 200 Tm³ at STP or 532 000 EJ). Courtesy of the National Oceanic and Atmospheric Administration (NOAA), http://oceanexplorer.noaa.gov/explorations/deepeast01/background/fire/media/carb_dist.html

Fig. 3

Assessed shale oil and gas basins in various locations across the globe as of June 2013. The shaded areas include both shale oil and shale gas. Courtesy of the EIA, http://www.eia.gov/todayinenergy/detail.cfm

Fig. 4

Known and inferred locations of gas hydrate occurrence. Map compiled by, and courtesy of, the US Geological Survey, http://www.usgs.gov